Roller grinding mill



May 2, 1939. 4 CARRUTHERS 2 ,156,620

ROLLER GRINDING MILL Filed Nov. 7, 1936 5 Sheets-Sheet 1 Fig.1

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c. :CARRUTHERS 2,156,620

ROLLER GRINDIN'G MILL Filed Nov. '7

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Y I g/441 2 ATTOR NEY May 2, 1939. CARRUTHERS 2,156,620

I RLLER GRINDING MILL Filed Nov. '7, 1936 5 Sheet-Sheet s A? /9 O H IVENTOR MM WMQZM ATTORNEY May 2, 1939. C. CARR-UTHERS 2,156,620

ROLLER GRINDING MILL Filed Nov. 7, 1936 5 Sheets-Sheet 4 INVENTOR ATTORNEY May 2, 1939. c. CARRUTHERS 2,156,620

ROLLER GRINDING MILL Filed Nov. 7, 1936 5 Sheets-Sheet 5 INVENTOR A TTORNE Y Patented May 2, 1939 UNITED STATES PATENT OFFHCE Application November 7, 1936, Serial No. 109,655 In Great Britain January 29, 1936 6 Claims.

This invention relates to roller grinding mills, and more particularly to grinding mills of the roll and breast bar type for the fine grinding or refining or finishing of paints, enamels, cellulose products, inks, etc., or mixtures which become fluid after mixing or grinding.

It is found that there is a tendency in such mills for the coarse material to work out to the ends of the bar and the roll and previously it has been proposed to collect such material separately and return it to the hopper for re-grinding, but more usually such material has been collected with the finely ground material. Where even small quantities of coarse particles are collected with the finer material, such lack of uniformity or homogeneity in the collected product may occur as may necessitate the re-grinding of the whole batch.

An aim of the present invention is to obviate these objections by giving the material successive stages of grinding in one and the same mill in such manner that the coarse material delivered at the ends of a bar at one stage of grinding is treated over a greater length of grinding bar during the succeeding stage or stages, so as to promote a better grinding of such material.

This I may achieve by associating with the roll a plurality of bars, the following bar, or each following bar, in the direction of rotation of the roll being of greater grinding length than the preceding one and extending beyond each end of the preceding bar so that the material which has passed between ends of one bar and the roll is free to spread and be treated by a greater length of roll at the next stage of grinding, and where three or more bars are used, the material is successively given such treatment, since the bars progressively increase in length from the first bar.

It is desirable to arrange the bars in spaced parallelism around the roll or otherwise to form spaces between the bars where they meet the roll, and the spaces between the bars may be utilised as pressure pockets as described for example in co-pending application Serial No. 109,653, filed November 7, 1936.

In order that the invention may be the more readily understood reference is hereinafter made to the accompanying drawings in which:

Fig. 1 is a plan view, Fig. 2 a front sectional elevation through line 22 of Fig. 1, Fig. 3 a transverse sectional view along line 33 of Fig. 1 illustrating a form of multiple bar mill according to this invention.

Fig. 4 is a plan view, Fig. 5 a front sectional view on the line 5-5 of Fig. 4 and Fig. 6 a more detailed plan view of a slightly modified form of multiple bar mill.

Figs. 7 and 8 are plan and side views of a sealing plate for the ends of the bars.

Figs. 9 and 10 are plan and side views of another part of the end sealing of the mill.

Fig. 11 shows a modified form of bar seal and Fig. 12 shows a modified form of the separator bars for spacing the grinding bars, an end view of these separator bars being drawn alongside each bar.

Fig. 13 is a detail View incorporating separator bars as shown in Fig. 12.

Fig. 14 is a detail view illustrating diagonal end seals for the progressively increasing lengths of bars and pockets.

Referring to Figs. 1 to 3, 6 and 13 the mill comprises a roll I, and four bars 2 which progressively increase in length as shown, the shortest being that nearest to the hopper.

Instead of using bars of diiferent lengths, four bars 4 of the same length may be employed as shown in Figs. 4 and 5, and the first three bars are each undercut at 5, 5a, 51) at each end to a greater extent than the next following one in the direction of rotation of the roll. The final bar should not be undercut. In this way the grinding length of the bars is progressively increased.

Appropriate provision is made for sealing off the ends of the bars and the roll, a convenient arrangement being one in which an end plate 6 curved at its lower edge 1 to the curvature of the roll is seated on the roll and is provided with a stepped portion 8 whose faces 9a, 9b, 9c, 9d lie against the ends of the actual grinding lengths of the bars. These faces also provide end sealing walls of pockets ll) which are formed between the bars and which are co-terminous with the end walls of the elfective length of the following grinding bar. If desired the seals may provide inclined end walls for the pockets as indicated by Ida in Fig. 14. Or the ends of the bars can be bevelled off as shown at (Fig. 11), and an. inclined plate llb (see Fig. 11) used to seal off the ends of the bars. The seal plate may be in two parts, that part H (see Figs. 3, 9 and 10) which seals oil the hopper having its edge l2 aligned with the edge l3 of the bar seal, a groove M for packing being provided in one part, e. g., part II, if desired.

The separator bars l8 whose lower edges lSa form the roofs of the pressure pockets may-take the variant form shown in Figs. 12 and 13. These bars are provided with lateral offsets 19 which seat on the hinged saddle bracket 20 which carries the grinding and separator bars, the offsets and medial projections 2| forming supports for the cylinder block of a liquid pressure system hereinafter described. The separator bars are stepped at 22 at each end to fit within the end seals, and may be transversely stepped at 23 to overhang the grinding bars. The pressure pocket, in advance of each grinding bar except the first, is thus defined by the back wall and front wall of successive grinding bars, the periphery of the roll and the overlying but spaced lower edges l8a of the spacer bars l8, and the vertical walls of the end seals 6.

The seal plates are provided with flexible sealing strips 30, 30a, 30b, 30c, (see Figs. 6 to 8) which engage with the ends of the grinding bars and separator bars IS. The screw 3! bearing against a part of the machine framework is screwed into a tapped hole 32 in the seal plate 6, whilst screws 33, 34 are screwed into a fixed part of the machine framework and their heads bear against the upper edge of the said plate and force said plate against the roll. The plate is secured to the separator bars by screws passing through holes 35, 35 which are elongated to enable the plate to be advanced towards the roll to take up wear. The seal plates 5 shown in Figs. 4 and 5, have a base portion 68 which is stepped as shown at 6|, in Fig. 4 similarly to the stepping of the plate shown in Figs. 6 and 8.

When it is desired to set up pressure of the material in the pockets or spaces between the bars, the pressure of the first and last bars at least, and if desired on all of the bars, may be independently or dependently adjustable and may be for example, mechanically or hydraulically applied pressure.

The bars may be mounted and arranged as described in the prior application aforesaid, or in any suitable manner.

The pressure may be applied hydraulically by the means illustrated wherein a series of plungers l5 and cylinders l6 are provided for each bar, the plungers being secured to or arranged to bear against the bars, and the cylinders being formed or located in a wall of a hydraulic pressure chamber H, which may be common to the plungers and cylinders of one bar or preferably, to the plungers and cylinders of all the bars.

The pressure on the bars, and more particularly on the first and last bars may be varied, other than by the aforesaid means, by making the final bar of less thickness than the first bar and applying the same pressure on the bars.

The end sealing plates can be stepped to seal ofl both the end wall of the bar and the end portion of the rear face of the following bar.

The intermediate bars, i. e., those between the first and the last bars, may make a relatively light contact with the roll, or in some cases may be in non-contacting setting whilst the first and last bars may be applied with greater contacting pressure, and where necessary relief orifices may be provided in accordance with my aforesaid c0- pending application Serial No. 109,653.

In order to assist the roll to carry the material past the several bars, the throat of the hopper may be arranged as described and claimed in the prior patent application Serial'No. 607,830 filed April 27, 1932, so as to cause the material in the throat to be under substantial pressure.

What I claim is:

.1. A multi-stage grinding roller mill for grinding fluid materials comprising a rotatable roll; a grinding bar cooperating therewith extending in the direction of the length of the roll; a second grinding bar following said first grinding bar in the direction of rotation of the roll and of greater length than the said first grinding bar so that the material which has passed through the ends of one grinding bar is free to spread and be treated by a greater length of bar in the next stage of grinding; and end seals engaging the roll and abutting the ends of said bars.

2. A multi-stage grinding roller mill for grinding fluid materials comprising a rotatable grinding roll; a plurality of grinding bars extending in the direction of the length of the roll and following each other in the direction of rotation of the roll, said bars being spaced from each other near the roll thereby providing material collecting pockets therebetween, each bar succeeding the first bar in the direction of rotation of the roll being of greater grinding length than the preceding bar and extending beyond each end of the preceding bar; and end seals engaging the roll and abutting the ends of said bars for closing the ends of the pocket against free exit of material.

3. A multi-stage grinding roller mill for grinding fluid materials comprising a rotatable roll, a grinding bar extending in the direction of the length of the roll; at least two further grinding bars following said first grinding bar in the direction of rotation of the roll; all of said bars being of different effective grinding length and arranged progressively in overlapped relation with the longest bar last in the direction of flow so that the material which has passed under the end portion of a preceding grinding bar is free to spread and be treated by a greater length of grinding bar in the next stage of grinding; and end seal means abutting the ends of the effective grinding lengths of said bars for sealing the said ends against escape of the material being processed.

4. A multi-stage grinding roller mill for grinding fluid materials comprising a rotatable roll; a grinding bar cooperating therewith extending in the direction of the length of the roll; at least one further grinding bar following said first grinding bar in the direction of rotation of the roll and of greater length than the preceding grinding bar so that the material which has passed under the end portions of one grinding bar is free to spread and be treated by a greater length of bar in the next stage of grinding; and seals abutting said bars, said seals being stepped to engage the bars of different lengths.

5. A multi-stage grinding roller mill for grinding fluid materials comprising a rotatable roll, a grinding bar having bevelled ends and extending in the direction of the length of the roll, at least one further grinding bar having bevelled ends and following said first grinding bar in the direction of rotation of the roll and of greater length than the preceding grinding bar so that the material which has passed under the end portions of one grinding bar is free to spread and be treated by a greater length of bar in the next stage of grinding; and end seal plates abutting said bars,said plates making a zone of contact with the roll oblique to the axis of the roll and engaging the bevelled ends of said bars of different lengths. i

6. A multi-stage grinding roller mill for grinding fluid materials comprising a rotatable roll; a plurality of grinding bars extending lengthwise the ends of one grinding bar is free to spread in the said pockets and be treated by the greater length of bar in the next following stage of grinding; and end seals abutting said bars, said end seals being shaped to engage the ends of said 5 bars of different lengths.

CHARLES CARRUTHERS. 

